1
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Nir-Arad O, Shlomi DH, Israelstam A, Amit T, Manukovsky N, Fialkov AB, Kaminker I. The CW-EPR Capabilities of a Dual DNP/EPR Spectrometer Operating at 14 and 7 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 360:107635. [PMID: 38401475 DOI: 10.1016/j.jmr.2024.107635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Revised: 12/24/2023] [Accepted: 02/07/2024] [Indexed: 02/26/2024]
Abstract
High-field electron paramagnetic resonance (EPR) measurements are indispensable for a better understanding of dynamic nuclear polarization (DNP), which relies on polarization transfer between electron and nuclear spins. DNP experiments are typically performed at high > 7 T magnetic fields and low ≤ 100 K temperatures, while EPR instrumentation capable of EPR measurements under these conditions is scarce. In this paper, we describe the CW EPR capabilities of a dual DNP/EPR spectrometer that is designed to carry out EPR experiments under "DNP conditions" at 14 and 7 T. In the first part, we present the design of this instrument, highlighting the choices made to allow for both DNP and EPR operations. The spectrometer uses a sweepable cryogen-free magnet with NMR-grade homogeneity, a closed-cycle cooling system, a quasi-optical induction mode bridge, and a superheterodyne receiver system. The probe design is optimized for low heat load and fast sample exchange under cryogenic conditions. The spectrometer can operate in frequency and field sweep modes, including wide field sweeps using the main coil of the magnet. In the second part, we present EPR spectra acquired over a wide range of samples and operating conditions, illustrating the CW EPR capabilities of the instrument.
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Affiliation(s)
- Orit Nir-Arad
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - David H Shlomi
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Amit Israelstam
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Tomer Amit
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Nurit Manukovsky
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Alexander B Fialkov
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
| | - Ilia Kaminker
- School of Chemistry, Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel.
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2
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Yang Q, Zhao J, Dreyer F, Krüger D, Chu A, Kern M, Blümich B, Anders J. A chip-based C-band ODNP platform. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2024; 358:107603. [PMID: 38142565 DOI: 10.1016/j.jmr.2023.107603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 11/24/2023] [Accepted: 11/28/2023] [Indexed: 12/26/2023]
Abstract
In this paper, we present a chip-based C-band ODNP platform centered around an NMR-on-a-chip transceiver and a printed microwave (MW) Alderman-Grant (AG) coil with a broadband tunable frequency range of 528MHz. The printable ODNP probe is optimized for a high input-power-to-magnetic-field conversion-efficiency, achieving a measured ODNP enhancement factor of -151 at microwave power levels of 33.3dBm corresponding to 2.1W. NMR measurements with and without microwave irradiation verify the functionality and the state-of-the-art performance of the proposed ODNP platform. The wide tuning range of the system allows for indirect measurements of the EPR signal of the DNP agent by sweeping the microwave excitation frequency and recording the resulting NMR signal. This feature can, e.g., be used to detect line broadening of the DNP agent. Moreover, we demonstrate experimentally that the wide tuning range of the new ODNP platform can be used to perform multi-tone microwave excitation for further signal enhancement: Using a 10mM TEMPOL solution, we improved the enhancement by a factor of two.
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Affiliation(s)
- Qing Yang
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Jianyu Zhao
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Frederik Dreyer
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Daniel Krüger
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany; John A. Paulson School of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, 02138, United States
| | - Anh Chu
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Michal Kern
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany
| | - Bernhard Blümich
- Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Worringerweg 2, Aachen, 52074, Germany
| | - Jens Anders
- Institute of Smart Sensors, University of Stuttgart, Pfafenwaldring 47, Stuttgart, 70569, Germany; Center for Integrated Quantum Science and Technology (IQ(ST)), Stuttgart, Germany; Institute for Microelectronics Stuttgart (IMS CHIPS), Stuttgart, Germany.
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3
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Cheney DJ, Wedge CJ. Sample volume effects in optical overhauser dynamic nuclear polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2022; 337:107170. [PMID: 35240365 DOI: 10.1016/j.jmr.2022.107170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/13/2022] [Accepted: 02/16/2022] [Indexed: 06/14/2023]
Abstract
The optical dynamic nuclear polarization (DNP) method has been proposed as an alternative to microwave pumping as a hyperpolarization method for solution-state NMR studies. Using continuous laser illumination to photogenerate triplet states in the presence of a persistent radical produces chemically-induced dynamic electron polarization (CIDEP) via the radical-triplet pair mechanism (RTPM), with cross-relaxation transferring this to nuclear hyperpolarization via an Overhauser mechanism. Numerical simulations have previously indicated that reducing the sample volume while maintaining a constant optical density can significantly increase the NMR signal enhancement, due to the larger steady-state concentration of triplets obtained. Here we provide the first experimental confirmation of these effects, producing a nearly five-fold increase in the optical DNP enhancement factor just by reducing the sample volume with optimal dye and radical concentrations adjusted for each optical path length. The results are supported with an in depth analysis of volume effects in the numerical model, with which they are in good qualitative agreement. These important observations will impact on the future development of the technique, with particular significance for attempts to apply DNP methods to increase sensitivity for volume-limited biological samples.
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Affiliation(s)
- Daniel J Cheney
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom
| | - Christopher J Wedge
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH, United Kingdom.
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4
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Zhang Z, Jiang Y, Pi H, Chen H, Liu C, Feng J, Liu M. THz-enhanced dynamic nuclear polarized liquid spectrometer. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2021; 330:107044. [PMID: 34352701 DOI: 10.1016/j.jmr.2021.107044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Revised: 07/21/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
Dynamic nuclear polarization (DNP) technology can be utilized to dramatically enhance NMR signal. In this paper, we report on the development of a self-constructed 5 T DNP spectrometer for liquid samples and the 13C DNP enhancement achieved with this spectrometer. The DNP spectrometer is comprised of a wide-bore superconducting magnet, a home-made console, a dual resonance probe and a self-built 140 GHz microwave source for the spectrometer. Specifically, a microwave source of traveling wave tube (TWT) amplifier has been developed, which can provide a maximum power output of 4.4 W and a wide frequency tuning range of 1 GHz. The excellent performance of our built liquid-state DNP spectrometer is verified by the observation of more than 100-fold DNP enhancement of the 13C NMR signal for liquid 13CCl4 sample. Our result shows the superiority of DNP technology in the liquid-state high-field NMR spectrometer.
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Affiliation(s)
- Zhekai Zhang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yi Jiang
- Institute of Applied Electronics of CAEP, Mianyang 621900, China
| | - Haiya Pi
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hongbin Chen
- Institute of Applied Electronics of CAEP, Mianyang 621900, China.
| | - Chaoyang Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Jiwen Feng
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China.
| | - Maili Liu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Center for Magnetic Resonance, Key Laboratory of Magnetic Resonance in Biological Systems, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, China; Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China
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5
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Sahin Solmaz N, Grisi M, Matheoud AV, Gualco G, Boero G. Single-Chip Dynamic Nuclear Polarization Microsystem. Anal Chem 2020; 92:9782-9789. [PMID: 32530638 PMCID: PMC9559634 DOI: 10.1021/acs.analchem.0c01221] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
![]()
Integration
of the sensitivity-relevant electronics of nuclear
magnetic resonance (NMR) and electron spin resonance (ESR) spectrometers
on a single chip is a promising approach to improve the limit of detection,
especially for samples in the nanoliter and subnanoliter range. Here,
we demonstrate the cointegration on a single silicon chip of the front-end
electronics of NMR and ESR detectors. The excitation/detection planar
spiral microcoils of the NMR and ESR detectors are concentric and
interrogate the same sample volume. This combination of sensors allows
one to perform dynamic nuclear polarization (DNP) experiments using
a single-chip-integrated microsystem having an area of about 2 mm2. In particular, we report 1H DNP-enhanced NMR
experiments on liquid samples having a volume of about 1 nL performed
at 10.7 GHz(ESR)/16 MHz(NMR). NMR enhancements as large as 50 are
achieved on TEMPOL/H2O solutions at room temperature. The
use of state-of-the-art submicrometer integrated circuit technologies
should allow the future extension of the single-chip DNP microsystem
approach proposed here up the THz(ESR)/GHz(NMR) region, corresponding
to the strongest static magnetic fields currently available. Particularly
interesting is the possibility to create arrays of such sensors for
parallel DNP-enhanced NMR spectroscopy of nanoliter and subnanoliter
samples.
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Affiliation(s)
- Nergiz Sahin Solmaz
- School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Marco Grisi
- School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Alessandro V. Matheoud
- School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Gabriele Gualco
- School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - Giovanni Boero
- School of Engineering, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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6
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Cheney DJ, Wedge CJ. Optically-generated Overhauser dynamic nuclear polarization: A numerical analysis. J Chem Phys 2020; 152:034202. [DOI: 10.1063/1.5133408] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Daniel J. Cheney
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, United Kingdom
| | - Christopher J. Wedge
- Department of Chemical Sciences, University of Huddersfield, Queensgate, Huddersfield, United Kingdom
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7
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Chen HY, Tycko R. Temperature-Dependent Nuclear Spin Relaxation Due to Paramagnetic Dopants Below 30 K: Relevance to DNP-Enhanced Magnetic Resonance Imaging. J Phys Chem B 2018; 122:11731-11742. [PMID: 30277390 PMCID: PMC6465147 DOI: 10.1021/acs.jpcb.8b07958] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dynamic nuclear polarization (DNP) can increase nuclear magnetic resonance (NMR) signal strengths by factors of 100 or more at low temperatures. In magnetic resonance imaging (MRI), signal enhancements from DNP potentially lead to enhancements in image resolution. However, the paramagnetic dopants required for DNP also reduce nuclear spin relaxation times, producing signal losses that may cancel the signal enhancements from DNP. Here we investigate the dependence of 1H NMR relaxation times, including T1ρ and T2, under conditions of Lee-Goldburg 1H-1H decoupling and pulsed spin locking, on temperature and dopant concentration in frozen solutions that contain the trinitroxide compound DOTOPA. We find that relaxation times become longer at temperatures below 10 K, where DOTOPA electron spins become strongly polarized at equilibrium in a 9.39 T magnetic field. We show that the dependences of relaxation times on temperature and DOTOPA concentration can be reproduced qualitatively (although not quantitatively) by detailed simulations of magnetic field fluctuations due to flip-flop transitions in a system of dipole-coupled electron spin magnetic moments. These results have implications for ongoing attempts to reach submicron resolution in inductively detected MRI at very low temperatures.
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Affiliation(s)
- Hsueh-Ying Chen
- Laboratory of Chemical Physics National Institute of Diabetes and Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
| | - Robert Tycko
- Laboratory of Chemical Physics National Institute of Diabetes and Digestive and Kidney Diseases , National Institutes of Health , Bethesda , Maryland 20892-0520 , United States
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8
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Franck JM, Han S. Overhauser Dynamic Nuclear Polarization for the Study of Hydration Dynamics, Explained. Methods Enzymol 2018; 615:131-175. [PMID: 30638529 DOI: 10.1016/bs.mie.2018.09.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
We outline the physical properties of hydration water that are captured by Overhauser Dynamic Nuclear Polarization (ODNP) relaxometry and explore the insights that ODNP yields about the water and the surface that this water is coupled to. As ODNP relies on the pairwise cross-relaxation between the electron spin of a spin probe and a proton nuclear spin of water, it captures the dynamics of single-particle diffusion of an ensemble of water molecules moving near the spin probe. ODNP principally utilizes the same physics as other nuclear magnetic resonance (NMR) relaxometry (i.e., relaxation measurement) techniques. However, in ODNP, electron paramagnetic resonance (EPR) excites the electron spins probes and their high net polarization acts as a signal amplifier. Furthermore, it renders ODNP parameters highly sensitive to water moving at rates commensurate with the EPR frequency of the spin probe (typically 10GHz). Also, ODNP selectively enhances the NMR signal contributions of water moving within close proximity to the spin label. As a result, ODNP can capture ps-ns movements of hydration waters with high sensitivity and locality, even in samples with protein concentrations as dilute as 10 µM. To date, the utility of the ODNP technique has been demonstrated for two major applications: the characterization of the spatial variation in the properties of the hydration layer of proteins or other surfaces displaying topological diversity, and the identification of structural properties emerging from highly disordered proteins and protein domains. The former has been shown to correlate well with the properties of hydration water predicted by MD simulations and has been shown capable of evaluating the hydrophilicity or hydrophobicity of a surface. The latter has been demonstrated for studies of an interhelical loop of proteorhodopsin, the partial structure of α-synuclein embedded at the lipid membrane surface, incipient structures adopted by tau proteins en route to fibrils, and the structure and hydration profile of a transmembrane peptide. This chapter focuses on offering a mechanistic understanding of the ODNP measurement and the molecular dynamics encoded in the ODNP parameters. In particular, it clarifies how the electron-nuclear dipolar coupling encodes information about the molecular dynamics in the nuclear spin self-relaxation and, more importantly, the electron-nuclear spin cross-relaxation rates. The clarification of the molecular dynamics underlying ODNP should assist in establishing a connection to theory and computer simulation that will offer far richer interpretations of ODNP results in future studies.
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Affiliation(s)
- John M Franck
- Department of Chemistry, Syracuse University, Syracuse, NY, United States.
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, CA, United States; Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, CA, United States
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9
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Biller JR, Barnes R, Han S. Perspective of Overhauser dynamic nuclear polarization for the study of soft materials. Curr Opin Colloid Interface Sci 2018. [DOI: 10.1016/j.cocis.2018.02.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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10
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One-thousand-fold enhancement of high field liquid nuclear magnetic resonance signals at room temperature. Nat Chem 2017. [DOI: 10.1038/nchem.2723] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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11
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Neudert O, Mattea C, Stapf S. A compact X-Band resonator for DNP-enhanced Fast-Field-Cycling NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 271:7-14. [PMID: 27526396 DOI: 10.1016/j.jmr.2016.08.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 08/05/2016] [Accepted: 08/06/2016] [Indexed: 06/06/2023]
Abstract
A new probehead was developed enabling Dynamic Nuclear Polarization (DNP)-enhanced Fast-Field-Cycling relaxometry at 340mT polarization field strength. It is based on a dielectric cavity resonator operating in the TM110 mode at 9.5GHz, which is suitable for both transverse and axial magnet geometries with a bore access of at least 20mm. The probehead includes a planar radio frequency coil for NMR detection and is compatible with standard 3mm NMR tubes. The resonator was assessed in terms of the microwave conversion factor and microwave-induced sample heating effects. Due to the compact size of the cavity, appreciable microwave magnetic field strengths were observed even with only moderate quality factors. Exemplary DNP experiments at 9.5GHz and 2.0GHz microwave frequency are compared for three different viscous samples, demonstrating the advantage of DNP at 9.5GHz for such systems. This new probehead enables new applications of DNP-enhanced Fast-Field-Cycling relaxometry of viscous and solid systems.
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Affiliation(s)
- Oliver Neudert
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany.
| | - Carlos Mattea
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany
| | - Siegfried Stapf
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany
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12
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Ravera E, Luchinat C, Parigi G. Basic facts and perspectives of Overhauser DNP NMR. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 264:78-87. [PMID: 26920833 DOI: 10.1016/j.jmr.2015.12.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 12/16/2015] [Accepted: 12/17/2015] [Indexed: 05/03/2023]
Abstract
After the first surprisingly large (1)H DNP enhancements of the water signal in aqueous solutions of nitroxide radicals observed at high magnetic fields, Overhauser DNP is gaining increasing attention for a number of applications now flourishing, showing the potentialities of this mechanism in solution and solid state NMR as well as in MRI. Unexpected Overhauser DNP enhancements in insulating solids were recently measured at 100K, with a magnitude which increases with the applied magnetic field. We recapitulate here the theoretical premises of Overhauser DNP in solution and analyze the effects of the various parameters on the efficacy of the mechanism, underlining the link between the DNP enhancements and the field dependent relaxation properties. Promisingly, more effective DNP enhancements are expected by exploiting the potentialities offered by (13)C detection and the use of supercritical fluids.
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Affiliation(s)
- Enrico Ravera
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy
| | - Claudio Luchinat
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy
| | - Giacomo Parigi
- Magnetic Resonance Center (CERM) and Department of Chemistry "Ugo Schiff", University of Florence, Italy.
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13
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van Bentum J, van Meerten B, Sharma M, Kentgens A. Perspectives on DNP-enhanced NMR spectroscopy in solutions. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2016; 264:59-67. [PMID: 26920831 DOI: 10.1016/j.jmr.2016.01.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 01/12/2016] [Accepted: 01/13/2016] [Indexed: 05/03/2023]
Abstract
More than 60 years after the seminal work of Albert Overhauser on dynamic nuclear polarization by dynamic cross relaxation of coupled electron-nuclear spin systems, the quest for sensitivity enhancement in NMR spectroscopy is as pressing as ever. In this contribution we will review the status and perspectives for dynamic nuclear polarization in the liquid state. An appealing approach seems to be the use of supercritical solvents that may allow an extension of the Overhauser mechanism towards common high magnetic fields. A complementary approach is the use of solid state DNP on frozen solutions, followed by a rapid dissolution or in-situ melting step and NMR detection with substantially enhanced polarization levels in the liquid state. We will review recent developments in the field and discuss perspectives for the near future.
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14
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Dale MW, Wedge CJ. Optically generated hyperpolarization for sensitivity enhancement in solution-state NMR spectroscopy. Chem Commun (Camb) 2016; 52:13221-13224. [DOI: 10.1039/c6cc06651h] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Using optical excitation to generate radical triplet pairs the sensitivity of solution-state NMR can be enhanced without microwave pumping.
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15
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Wang X, Isley Iii WC, Salido SI, Sun Z, Song L, Tsai KH, Cramer CJ, Dorn HC. Optimization and prediction of the electron-nuclear dipolar and scalar interaction in 1H and 13C liquid state dynamic nuclear polarization. Chem Sci 2015; 6:6482-6495. [PMID: 30090267 PMCID: PMC6054052 DOI: 10.1039/c5sc02499d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 07/25/2015] [Indexed: 12/19/2022] Open
Abstract
During the last 10-15 years, dynamic nuclear polarization (DNP) has evolved as a powerful tool for hyperpolarization of NMR and MRI nuclides. However, it is not as well appreciated that solution-state dynamic nuclear polarization is a powerful approach to study intermolecular interactions in solution. For solutions and fluids, the 1H nuclide is usually dominated by an Overhauser dipolar enhancement and can be significantly increased by decreasing the correlation time (τc) of the substrate/nitroxide interaction by utilizing supercritical fluids (SF CO2). For molecules containing the ubiquitous 13C nuclide, the Overhauser enhancement is usually a profile of both scalar and dipolar interactions. For carbon atoms without an attached hydrogen, a dipolar enhancement usually dominates as we illustrate for sp2 hybridized carbons in the fullerenes, C60 and C70. However, the scalar interaction is dependent on a Fermi contact interaction which does not have the magnetic field dependence inherent in the dipolar interaction. For a comprehensive range of molecular systems we show that molecules that exhibit weakly acidic complexation interaction(s) with nitroxides provide corresponding large scalar enhancements. For the first time, we report that sp hybridized (H-C) alkyne systems, for example, the phenylacetylene-nitroxide system exhibit very large scalar dominated enhancements. Finally, we demonstrate for a wide range of molecular systems that the Fermi contact interaction can be computationally predicted via electron-nuclear hyperfine coupling and correlated with experimental 13C DNP enhancements.
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Affiliation(s)
- X Wang
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - W C Isley Iii
- Department of Chemistry and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455-0431 , USA .
| | - S I Salido
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - Z Sun
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - L Song
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - K H Tsai
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
| | - C J Cramer
- Department of Chemistry and Minnesota Supercomputing Institute , University of Minnesota , Minneapolis , Minnesota 55455-0431 , USA .
| | - H C Dorn
- Department of Chemistry , Virginia Tech , Blacksburg , Virginia 24061 , USA .
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16
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Küçük SE, Biktagirov T, Sezer D. Carbon and proton Overhauser DNP from MD simulations and ab initio calculations: TEMPOL in acetone. Phys Chem Chem Phys 2015; 17:24874-84. [PMID: 26343351 DOI: 10.1039/c5cp04405g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A computational analysis of the Overhauser effect is reported for the proton, methyl carbon, and carbonyl carbon nuclei of liquid acetone doped with the nitroxide radical TEMPOL. A practical methodology for calculating the dynamic nuclear polarization (DNP) coupling factors by accounting for both dipole-dipole and Fermi-contact interactions is presented. The contribution to the dipolar spectral density function of nuclear spins that are not too far from TEMPOL is computed through classical molecular dynamics (MD) simulations, whereas the contribution of distant spins is included analytically. Fermi contacts are obtained by subjecting a few molecules from every MD snapshot to ab initio quantum mechanical calculations. Scalar interaction is found to be an essential part of the (13)C Overhauser DNP. While mostly detrimental to the carbonyl carbon of acetone it is predicted to result in large enhancements of the methyl carbon signal at magnetic fields of 9 T and beyond. In contrast, scalar coupling is shown to be negligible for the protons of acetone. The additional influence of proton polarization on the carbon DNP (three-spin effect) is also analyzed computationally. Its effect, however, is concluded to be practically insignificant for liquid acetone.
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Affiliation(s)
- Sami Emre Küçük
- Faculty of Engineering and Natural Sciences, Sabanc University, Orhanl-Tuzla, 34956 Istanbul, Turkey.
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Kaminker I, Barnes R, Han S. Overhauser Dynamic Nuclear Polarization Studies on Local Water Dynamics. Methods Enzymol 2015; 564:457-83. [PMID: 26477261 DOI: 10.1016/bs.mie.2015.06.040] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Overhauser dynamic nuclear polarization (ODNP) is an emerging technique for quantifying translational water dynamics in the vicinity (<1 nm) of stable radicals that can be chemically attached to macromolecules of interest. This has led to many in-depth and enlightening studies of hydration water of biomolecules, revolving around the role of solvent dynamics in the structure and function of proteins, nucleic acids, and lipid bilayer membranes. Still to date, a complete and fully automated ODNP instrument is not commercialized. The purpose of this chapter is to share the technical know-how of the hardware, theory, measurement, and data analysis method needed to successfully utilize and disseminate the ODNP technique.
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Affiliation(s)
- Ilia Kaminker
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA
| | - Ryan Barnes
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California Santa Barbara, Santa Barbara, California, USA; Department of Chemical Engineering, University of California Santa Barbara, Santa Barbara, California, USA.
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Ardenkjaer-Larsen JH, Boebinger GS, Comment A, Duckett S, Edison AS, Engelke F, Griesinger C, Griffin RG, Hilty C, Maeda H, Parigi G, Prisner T, Ravera E, van Bentum J, Vega S, Webb A, Luchinat C, Schwalbe H, Frydman L. Facing and Overcoming Sensitivity Challenges in Biomolecular NMR Spectroscopy. Angew Chem Int Ed Engl 2015; 54:9162-85. [PMID: 26136394 PMCID: PMC4943876 DOI: 10.1002/anie.201410653] [Citation(s) in RCA: 217] [Impact Index Per Article: 24.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2014] [Revised: 01/26/2015] [Indexed: 11/07/2022]
Abstract
In the Spring of 2013, NMR spectroscopists convened at the Weizmann Institute in Israel to brainstorm on approaches to improve the sensitivity of NMR experiments, particularly when applied in biomolecular settings. This multi-author interdisciplinary Review presents a state-of-the-art description of the primary approaches that were considered. Topics discussed included the future of ultrahigh-field NMR systems, emerging NMR detection technologies, new approaches to nuclear hyperpolarization, and progress in sample preparation. All of these are orthogonal efforts, whose gains could multiply and thereby enhance the sensitivity of solid- and liquid-state experiments. While substantial advances have been made in all these areas, numerous challenges remain in the quest of endowing NMR spectroscopy with the sensitivity that has characterized forms of spectroscopies based on electrical or optical measurements. These challenges, and the ways by which scientists and engineers are striving to solve them, are also addressed.
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Affiliation(s)
- Jan-Henrik Ardenkjaer-Larsen
- GE Healthcare, Broendby, Denmark; Department of Electrical Engineering, Technical University of Denmark, Danish Research Centre for Magnetic Resonance, Copenhagen University Hospital Hvidovre (Denmark)
| | - Gregory S Boebinger
- U.S. National High Magnetic Field Lab, Florida State University, Tallahassee, FL 32310 (USA)
| | - Arnaud Comment
- Institute of Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne, Lausanne (Switzerland)
| | - Simon Duckett
- Department of Chemistry, University of York, Heslington, York, YO10 5DD (UK)
| | - Arthur S Edison
- Department of Biochemistry & Molecular Biology, University of Florida, Gainesville, FL 32610 (USA)
| | | | | | - Robert G Griffin
- Department of Chemistry and Francis Bitter Magnet Lab, MIT, Cambridge, MA 02139-4703 (USA)
| | - Christian Hilty
- Department of Chemistry, Texas A&M University, College Station (USA)
| | - Hidaeki Maeda
- Riken Center for Life Science Technologies, Yokohama, Kanagawa (Japan)
| | - Giacomo Parigi
- CERM and Department of Chemistry, University of Florence, Sesto Fiorentino (Italy)
| | - Thomas Prisner
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main (Germany)
| | - Enrico Ravera
- CERM and Department of Chemistry, University of Florence, Sesto Fiorentino (Italy)
| | | | - Shimon Vega
- Chemical Physics Department, Weizmann Institute of Science, Rehovot (Israel)
| | - Andrew Webb
- Department of Radiology, C. J. Gorter Center for High Field MRI, Leiden University Medical Center (The Netherlands)
| | - Claudio Luchinat
- CERM and Department of Chemistry, University of Florence, Sesto Fiorentino (Italy).
| | - Harald Schwalbe
- Center for Biomolecular Magnetic Resonance (BMRZ), Goethe University Frankfurt, Max-von-Laue-Strasse 7, 60438 Frankfurt am Main (Germany).
| | - Lucio Frydman
- Chemical Physics Department, Weizmann Institute of Science, Rehovot (Israel).
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Ardenkjaer-Larsen JH, Boebinger GS, Comment A, Duckett S, Edison AS, Engelke F, Griesinger C, Griffin RG, Hilty C, Maeda H, Parigi G, Prisner T, Ravera E, van Bentum J, Vega S, Webb A, Luchinat C, Schwalbe H, Frydman L. Neue Ansätze zur Empfindlichkeitssteigerung in der biomolekularen NMR-Spektroskopie. Angew Chem Int Ed Engl 2015. [DOI: 10.1002/ange.201410653] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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20
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Küçük SE, Neugebauer P, Prisner TF, Sezer D. Molecular simulations for dynamic nuclear polarization in liquids: a case study of TEMPOL in acetone and DMSO. Phys Chem Chem Phys 2015; 17:6618-28. [PMID: 25665728 DOI: 10.1039/c4cp05832a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A computational strategy for calibrating, validating and analyzing molecular dynamics (MD) simulations to predict dynamic nuclear polarization (DNP) coupling factors and relaxivities of proton spins is presented. Simulations of the polarizing agent TEMPOL in liquid acetone and DMSO are conducted at low (infinite dilution) and high (1 M) concentrations of the free radical. Because DNP coupling factors and relaxivities are sensitive to the time scales of the molecular motions, the MD simulations are calibrated to reproduce the bulk translational diffusion coefficients of the pure solvents. The simulations are then validated by comparing with experimental dielectric relaxation spectra, which report on the rotational dynamics of the molecular electric dipole moments. The analysis consists of calculating spectral density functions (SDFs) of the magnetic dipole-dipole interaction between the electron spin of TEMPOL and nuclear spins of the solvent protons. Here, MD simulations are used in combination with an analytically tractable model of molecular motion. While the former provide detailed information at relatively short spin-spin distances, the latter includes contributions at large separations, all the way to infinity. The relaxivities calculated from the SDFs of acetone and DMSO are in excellent agreement with experiments at 9.2 T. For DMSO we calculate a coupling factor in agreement with experiment while for acetone we predict a value that is larger by almost 50%, suggesting a possibility for experimental improvement.
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Affiliation(s)
- Sami Emre Küçük
- Faculty of Engineering and Natural Sciences, Sabancı University, Orhanlı-Tuzla, 34956 Istanbul, Turkey.
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21
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Terekhov M, Krummenacker J, Denysenkov V, Gerz K, Prisner T, Schreiber LM. Characterization and optimization of the visualization performance of continuous flow overhauser DNP hyperpolarized water MRI: Inversion recovery approach. Magn Reson Med 2015; 75:985-96. [PMID: 25884985 DOI: 10.1002/mrm.25574] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Revised: 11/11/2014] [Accepted: 11/15/2014] [Indexed: 01/08/2023]
Abstract
PURPOSE Overhauser dynamic nuclear polarization (DNP) allows the production of liquid hyperpolarized substrate inside the MRI magnet bore as well as its administration in continuous flow mode to acquire MR images with enhanced signal-to-noise ratio. We implemented inversion recovery preparation in order to improve contrast-to-noise ratio and to quantify the overall imaging performance of Overhauser DNP-enhanced MRI. METHOD The negative enhancement created by DNP in combination with inversion recovery (IR) preparation allows canceling selectively the signal originated from Boltzmann magnetization and visualizing only hyperpolarized fluid. The theoretical model describing gain of MR image intensity produced by steady-state continuous flow DNP hyperpolarized magnetization was established and proved experimentally. RESULTS A precise quantification of signal originated purely from DNP hyperpolarization was achieved. A temperature effect on longitudinal relaxation had to be taken into account to fit experimental results with numerical prediction. CONCLUSION Using properly adjusted IR preparation, the complete zeroing of thermal background magnetization was achieved, providing an essential increase of contrast-to-noise ratio of DNP-hyperpolarized water images. To quantify and optimize the steady-state conditions for MRI with continuous flow DNP, an approach similar to that incorporating transient-state thermal magnetization equilibrium in spoiled fast field echo imaging sequences can be used.
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Affiliation(s)
- Maxim Terekhov
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - Jan Krummenacker
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany.,Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Vasyl Denysenkov
- Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Kathrin Gerz
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
| | - Thomas Prisner
- Institute of Physical and Theoretical Chemistry, Center for Bimolecular Magnetic Resonance Goethe-University, Frankfurt am Main, Germany
| | - Laura Maria Schreiber
- Section of Medical Physics, Department of Radiology, University Medical Center Mainz, Mainz, Germany
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Abstract
Gas chromatography-mass spectrometry (GC-MS) has been widely used in metabonomics analyses of biofluid samples. Biofluids provide a wealth of information about the metabolism of the whole body and from multiple regions of the body that can be used to study general health status and organ function. Blood serum and blood plasma, for example, can provide a comprehensive picture of the whole body, while urine can be used to monitor the function of the kidneys, and cerebrospinal fluid (CSF) will provide information about the status of the brain and central nervous system (CNS). Different methods have been developed for the extraction of metabolites from biofluids, these ranging from solvent extracts, acids, heat denaturation, and filtration. These methods vary widely in terms of efficiency of protein removal and in the number of metabolites extracted. Consequently, for all biofluid-based metabonomics studies, it is vital to optimize and standardize all steps of sample preparation, including initial extraction of metabolites. In this chapter, recommendations are made of the optimum experimental conditions for biofluid samples for GC-MS, with a particular focus on blood serum and plasma samples.
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23
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Enkin N, Liu G, Gimenez-Lopez MDC, Porfyrakis K, Tkach I, Bennati M. A high saturation factor in Overhauser DNP with nitroxide derivatives: the role of 14N nuclear spin relaxation. Phys Chem Chem Phys 2015; 17:11144-9. [DOI: 10.1039/c5cp00935a] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Functionalization of nitroxide radicals leads to an increase of the saturation factor and of the Overhauser DNP enhancement.
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Affiliation(s)
- Nikolay Enkin
- RG EPR spectroscopy
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Guoquan Liu
- RG EPR spectroscopy
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | | | | | - Igor Tkach
- RG EPR spectroscopy
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
| | - Marina Bennati
- RG EPR spectroscopy
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen
- Germany
- Department of Chemistry
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24
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Emwas AHM, Al-Talla ZA, Kharbatia NM. Sample collection and preparation of biofluids and extracts for gas chromatography-mass spectrometry. Methods Mol Biol 2015; 1277:75-90. [PMID: 25677148 DOI: 10.1007/978-1-4939-2377-9_7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To maximize the utility of gas chromatography-mass spectrometry (GC-MS) in metabonomics research, all stages of the experimental design should be standardized, including sample collection, storage, preparation, and sample separation. Moreover, the prerequisite for any GC-MS analysis is that a compound must be volatile and thermally stable if it is to be analyzed using this technique. Since many metabolites are nonvolatile and polar in nature, they are not readily amenable to analysis by GC-MS and require initial chemical derivatization of the polar functional groups in order to reduce the polarity and to increase the thermal stability and volatility of the analytes. In this chapter, an overview is presented of the optimum approach to sample collection, storage, and preparation for gas chromatography-mass spectrometry-based metabonomics with particular focus on urine samples as example of biofluids.
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Affiliation(s)
- Abdul-Hamid M Emwas
- NMR Core Lab, King Abdullah University of Science and Technology, Room 0149, 23955-6900, Thuwal, Kingdom of Saudi Arabia,
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25
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Neudert O, Raich HP, Mattea C, Stapf S, Münnemann K. An Alderman-Grant resonator for S-Band Dynamic Nuclear Polarization. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2014; 242:79-85. [PMID: 24607825 DOI: 10.1016/j.jmr.2014.02.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2013] [Revised: 01/31/2014] [Accepted: 02/01/2014] [Indexed: 06/03/2023]
Abstract
An Alderman-Grant resonator with resonance at 2GHz (S-Band) was simulated, developed and constructed for Dynamic Nuclear Polarization (DNP) experiments at 73mT. The resonator fits into magnet bores with a minimum diameter of 20mm and is compatible with standard 3mm NMR tubes. The compact resonator design achieves good separation of electric and magnetic fields and therefore can be used with comparatively large sample volumes with only small sample heating effects comparable to those obtained with optimized X- and W-Band DNP setups. The saturation efficiency and sample heating effects were investigated for Overhauser DNP experiments of aqueous solutions of TEMPOL radical, showing relative saturation better than 0.9 and sample heating not exceeding a few Kelvin even at high microwave power and long irradiation time. An application is demonstrated, combining the DNP setup with a commercial fast field cycling NMR relaxometer. Using this resonator design at low microwave frequencies can provide DNP polarization for a class of low-field and time-domain NMR experiments and therefore may enable new applications that benefit from increased sensitivity.
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Affiliation(s)
- Oliver Neudert
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
| | - Hans-Peter Raich
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
| | - Carlos Mattea
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany.
| | - Siegfried Stapf
- Institute of Physics, Ilmenau University of Technology, D-98693 Ilmenau, Germany.
| | - Kerstin Münnemann
- Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz, Germany.
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26
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Koonjoo N, Parzy E, Massot P, Lepetit-Coiffé M, Marque SRA, Franconi JM, Thiaudiere E, Mellet P. In vivo Overhauser-enhanced MRI of proteolytic activity. CONTRAST MEDIA & MOLECULAR IMAGING 2014; 9:363-71. [PMID: 24729587 DOI: 10.1002/cmmi.1586] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/21/2013] [Accepted: 10/31/2013] [Indexed: 01/22/2023]
Abstract
There is an increasing interest in developing novel imaging strategies for sensing proteolytic activities in intact organisms in vivo. Overhauser-enhanced MRI (OMRI) offers the possibility to reveal the proteolysis of nitroxide-labeled macromolecules thanks to a sharp decrease of the rotational correlation time of the nitroxide moiety upon cleavage. In this paper, this concept is illustrated in vivo at 0.2 T using nitroxide-labeled elastin orally administered in mice. In vitro, this elastin derivative was OMRI-visible and gave rise to high Overhauser enhancements (19-fold at 18 mm nitroxide) upon proteolysis by pancreatic porcine elastase. In vivo three-dimensional OMRI detection of proteolysis was carried out. A keyhole fully balanced steady-state free precession sequence was used, which allowed 3D OMRI acquisition within 20 s at 0.125 mm(3) resolution. About 30 min after mouse gavage, proteolysis was detected in the duodenum, where Overhauser enhancements were 7.2 ± 2.4 (n = 7) and was not observed in the stomach. Conversely, orally administered free nitroxides or pre-digested nitroxide-labeled elastin were detected in the mouse's stomach by OMRI. Combined with specific molecular probes, this Overhauser-enhanced MRI technique can be used to evaluate unregulated proteolytic activities in various models of experimental diseases and for drug testing.
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Affiliation(s)
- Neha Koonjoo
- Centre de Résonance Magnétique des Systèmes Biologiques, UMR 5536 CNRS Université Bordeaux Segalen, Bordeaux, France
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27
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Enkin N, Liu G, Tkach I, Bennati M. High DNP efficiency of TEMPONE radicals in liquid toluene at low concentrations. Phys Chem Chem Phys 2014; 16:8795-800. [DOI: 10.1039/c4cp00854e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Dynamic nuclear polarization in liquid toluene with TEMPONE radicals leads to high NMR signal enhancements at low polarizer concentrations.
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Affiliation(s)
- Nikolay Enkin
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Guoquan Liu
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Igor Tkach
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
| | - Marina Bennati
- Max-Planck Institute for Biophysical Chemistry
- 37077 Göttingen, Germany
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28
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Sezer D. Rationalizing Overhauser DNP of nitroxide radicals in water through MD simulations. Phys Chem Chem Phys 2014; 16:1022-32. [DOI: 10.1039/c3cp53565g] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Franck JM, Pavlova A, Scott JA, Han S. Quantitative cw Overhauser effect dynamic nuclear polarization for the analysis of local water dynamics. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2013; 74:33-56. [PMID: 24083461 PMCID: PMC3798041 DOI: 10.1016/j.pnmrs.2013.06.001] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2012] [Accepted: 01/10/2013] [Indexed: 05/03/2023]
Abstract
Liquid state Overhauser effect Dynamic Nuclear Polarization (ODNP) has experienced a recent resurgence of interest. The ODNP technique described here relies on the double resonance of electron spin resonance (ESR) at the most common, i.e. X-band (∼10GHz), frequency and ¹H nuclear magnetic resonance (NMR) at ∼15 MHz. It requires only a standard continuous wave (cw) ESR spectrometer with an NMR probe inserted or built into an X-band cavity. We focus on reviewing a new and powerful manifestation of ODNP as a high frequency NMR relaxometry tool that probes dipolar cross relaxation between the electron spins and the ¹H nuclear spins at X-band frequencies. This technique selectively measures the translational mobility of water within a volume extending 0.5-1.5 nm outward from a nitroxide radical spin probe that is attached to a targeted site of a macromolecule. It allows one to study the dynamics of water that hydrates or permeates the surface or interior of proteins, polymers, and lipid membrane vesicles. We begin by reviewing the recent advances that have helped develop ODNP into a tool for mapping the dynamic landscape of hydration water with sub-nanometer locality. In order to bind this work coherently together and to place it in the context of the extensive body of research in the field of NMR relaxometry, we then rephrase the analytical model and extend the description of the ODNP-derived NMR signal enhancements. This extended model highlights several aspects of ODNP data analysis, including the importance of considering all possible effects of microwave sample heating, the need to consider the error associated with various relaxation rates, and the unique ability of ODNP to probe the electron-¹H cross-relaxation process, which is uniquely sensitive to fast (tens of ps) dynamical processes. By implementing the relevant corrections in a stepwise fashion, this paper draws a consensus result from previous ODNP procedures and then shows how such data can be further corrected to yield clear and reproducible saturation of the NMR hyperpolarization process. Finally, drawing on these results, we broadly survey the previous ODNP dynamics literature. We find that the vast number of published, empirical hydration dynamics data can be reproducibly classified into regimes of surface, interfacial, vs. buried water dynamics.
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Affiliation(s)
- John M Franck
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA, USA
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Cheng CY, Han S. Dynamic Nuclear Polarization Methods in Solids and Solutions to Explore Membrane Proteins and Membrane Systems. Annu Rev Phys Chem 2013; 64:507-32. [DOI: 10.1146/annurev-physchem-040412-110028] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Membrane proteins regulate vital cellular processes, including signaling, ion transport, and vesicular trafficking. Obtaining experimental access to their structures, conformational fluctuations, orientations, locations, and hydration in membrane environments, as well as the lipid membrane properties, is critical to understanding their functions. Dynamic nuclear polarization (DNP) of frozen solids can dramatically boost the sensitivity of current solid-state nuclear magnetic resonance tools to enhance access to membrane protein structures in native membrane environments. Overhauser DNP in the solution state can map out the local and site-specific hydration dynamics landscape of membrane proteins and lipid membranes, critically complementing the structural and dynamics information obtained by electron paramagnetic resonance spectroscopy. Here, we provide an overview of how DNP methods in solids and solutions can significantly increase our understanding of membrane protein structures, dynamics, functions, and hydration in complex biological membrane environments.
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Affiliation(s)
- Chi-Yuan Cheng
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
| | - Songi Han
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106
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31
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Franck JM, Scott JA, Han S. Nonlinear scaling of surface water diffusion with bulk water viscosity of crowded solutions. J Am Chem Soc 2013; 135:4175-8. [PMID: 23347324 PMCID: PMC3785640 DOI: 10.1021/ja3112912] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The translational hydration dynamics within 0.5-1.5 nm of the surface of a DPPC liposome, a model biomacromolecular surface, is analyzed by the recently developed Overhauser dynamic nuclear polarization (ODNP) technique. We find that dramatic changes to the bulk solvent cause only weak changes in the surface hydration dynamics. Specifically, both a >10-fold increase in bulk viscosity and the restriction of diffusion by confinement on a multiple nm length-scale change the local translational diffusion coefficient of the surface water surrounding the lipid bilayer by <2.5-fold. By contrast, previous ODNP studies have shown that changes to the biomacromolecular surface induced by folding, binding, or aggregation can cause local hydration dynamics to vary by factors of up to 30. We suggest that the surface topology and chemistry at the ≤1.5 nm scale, rather than the characteristics of the solvent, nearly exclusively determine the macromolecule's surface hydration dynamics.
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Affiliation(s)
- John M. Franck
- Dept. of Chemistry and Biochemistry, University of California, Santa Barbara
| | - John A. Scott
- Dept. of Chemistry and Biochemistry, University of California, Santa Barbara
| | - Songi Han
- Dept. of Chemistry and Biochemistry, University of California, Santa Barbara
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32
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Neugebauer P, Krummenacker JG, Denysenkov VP, Parigi G, Luchinat C, Prisner TF. Liquid state DNP of water at 9.2 T: an experimental access to saturation. Phys Chem Chem Phys 2013; 15:6049-56. [PMID: 23493879 DOI: 10.1039/c3cp44461a] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We have performed liquid state ("Overhauser") Dynamic Nuclear Polarization (DNP) experiments at high magnetic field (9.2 T, corresponding to 260 GHz EPR and 400 MHz (1)H-NMR resonance frequency) on aqueous solutions of (14)N-TEMPOL nitroxide radicals. Integrated signal enhancements exceeding -80 were observed for the water protons at microwave superheated temperatures (160 °C) and still -14 at ambient temperatures (45 °C) relevant to biological applications. Different contributions contributing to the DNP enhancement such as saturation factor, leakage factor and sample temperature under microwave irradiation could be determined independently for a high spin concentration of 1 M, allowing the calculation of the coupling factors as a function of temperature and a quantitative comparison of this parameter with values derived from field dependent relaxation measurements or predictions from MD simulation.
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Affiliation(s)
- Petr Neugebauer
- Institute of Physical and Theoretical Chemistry and Center for Biomolecular Magnetic Resonance, Goethe-University, Max-von-Laue-Str. 7, 60438, Frankfurt am Main, Germany
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Abstract
Nuclear magnetic resonance (NMR) spectroscopy is one of the most commonly used spectroscopic techniques to obtain information on the structure and dynamics of biological and chemical materials. A variety of samples can be studied including solutions, crystalline solids, powders and hydrated protein extracts. However, biological NMR spectroscopy is limited to concentrated samples, typically in the millimolar range, due to its intrinsic low sensitivity compared to other techniques such as fluorescence or electron paramagnetic resonance (EPR) spectroscopy.Dynamic nuclear polarization (DNP) is a method that increases the sensitivity of NMR by several orders of magnitude. It exploits a polarization transfer from unpaired electrons to neighboring nuclei which leads to an absolute increase of the signal-to-noise ratio (S/N). Consequently, biological samples with much lower concentrations can now be studied in hours or days compared to several weeks.This chapter will explain the different types of DNP enhanced NMR experiments, focusing primarily on solid-state magic angle spinning (MAS) DNP, its applications, and possible means of improvement.
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34
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Neudert O, Mattea C, Spiess HW, Stapf S, Münnemann K. A comparative study of 1H and 19F Overhauser DNP in fluorinated benzenes. Phys Chem Chem Phys 2013; 15:20717-26. [DOI: 10.1039/c3cp52912f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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35
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Doll A, Bordignon E, Joseph B, Tschaggelar R, Jeschke G. Liquid state DNP for water accessibility measurements on spin-labeled membrane proteins at physiological temperatures. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 222:34-43. [PMID: 22820007 DOI: 10.1016/j.jmr.2012.06.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 06/04/2012] [Accepted: 06/06/2012] [Indexed: 05/03/2023]
Abstract
We demonstrate the application of continuous wave dynamic nuclear polarization (DNP) at 0.35 T for site-specific water accessibility studies on spin-labeled membrane proteins at concentrations in the 10-100 μM range. The DNP effects at such low concentrations are weak and the experimentally achievable dynamic nuclear polarizations can be below the equilibrium polarization. This sensitivity problem is solved with an optimized home-built DNP probe head consisting of a dielectric microwave resonator and a saddle coil as close as possible to the sample. The performance of the probe head is demonstrated with both a modified pulsed EPR spectrometer and a dedicated CW EPR spectrometer equipped with a commercial NMR console. In comparison to a commercial pulsed ENDOR resonator, the home-built resonator has an FID detection sensitivity improvement of 2.15 and an electron spin excitation field improvement of 1.2. The reproducibility of the DNP results is tested on the water soluble maltose binding protein MalE of the ABC maltose importer, where we determine a net standard deviation of 9% in the primary DNP data in the concentration range between 10 and 100 μM. DNP parameters are measured in a spin-labeled membrane protein, namely the vitamin B(12) importer BtuCD in both detergent-solubilized and reconstituted states. The data obtained in different nucleotide states in the presence and absence of binding protein BtuF reveal the applicability of this technique to qualitatively extract water accessibility changes between different conformations by the ratio of primary DNP parameters ϵ. The ϵ-ratio unveils the physiologically relevant transmembrane communication in the transporter in terms of changes in water accessibility at the cytoplasmic gate of the protein induced by both BtuF binding at the periplasmic region of the transporter and ATP binding at the cytoplasmic nucleotide binding domains.
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Affiliation(s)
- Andrin Doll
- ETH Zurich, Laboratory of Physical Chemistry, Wolfgang-Pauli-Str. 10, CH-8093 Zurich, Switzerland
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Griesinger C, Bennati M, Vieth HM, Luchinat C, Parigi G, Höfer P, Engelke F, Glaser SJ, Denysenkov V, Prisner TF. Dynamic nuclear polarization at high magnetic fields in liquids. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2012; 64:4-28. [PMID: 22578315 DOI: 10.1016/j.pnmrs.2011.10.002] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Accepted: 10/11/2011] [Indexed: 05/03/2023]
Affiliation(s)
- C Griesinger
- MPI for Biophysical Chemistry Göttingen, Am Fassberg 11, 37077 Göttingen, Germany
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Türke MT, Bennati M. Comparison of Overhauser DNP at 0.34 and 3.4 T with Frémy's Salt. APPLIED MAGNETIC RESONANCE 2012; 43:129-138. [PMID: 22815593 PMCID: PMC3396338 DOI: 10.1007/s00723-012-0362-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2012] [Revised: 05/11/2012] [Indexed: 05/05/2023]
Abstract
Dynamic nuclear polarization (DNP) is investigated in the liquid state using a model system of Frémy's salt dissolved in water. Nuclear magnetic resonance signal enhancements at 0.34 and 3.4 T of the bulk water protons are recorded as a function of the irradiation time and the polarizer concentration. The build-up rates are consistent with the T(1n) of the observed water protons at room temperature (for 9 GHz/0.34 T) and for about 50 ± 10 °C at 94 GHz/3.4 T. At 94 GHz/3.4 T, we observe in our setup a maximal enhancement of -50 at 25 mM polarizer concentration. The use of Frémy's salt allows the determination of the saturation factors at 94 GHz by pulsed ELDOR experiments. The results are well consistent with the Overhauser DNP mechanism and indicate that higher enhancements at this intermediate frequency require higher sample temperatures.
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Affiliation(s)
- M.-T. Türke
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
| | - M. Bennati
- Max Planck Institute for Biophysical Chemistry, 37077 Göttingen, Germany
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Denysenkov V, Prisner T. Liquid state Dynamic Nuclear Polarization probe with Fabry-Perot resonator at 9.2 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 217:1-5. [PMID: 22386647 DOI: 10.1016/j.jmr.2012.01.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2011] [Revised: 01/23/2012] [Accepted: 01/25/2012] [Indexed: 05/31/2023]
Abstract
Recent achievements in liquid state DNP at high magnetic fields showing significant enhancements on aqueous solutions have initiated strong interest in possible applications of this method to biomolecular research. However, in situ DNP of biomolecules at ambient temperatures is a challenging task due to high microwave losses leading to excessive sample heating. To avoid such heating the sample volume has to be reduced strongly to keep it away from the electric component of the microwave field. A helical double resonance structure, used for the first demonstrations of the applicability of Overhauser DNP to aqueous solutions at high magnetic fields (9.2 T), restricted the sample size to a very small volume of 2 nl. Together with a poor spectral resolution this resulted in small overall signal amplitude, hampering observations of biomolecules. Here we present a new type of the double resonance structure for liquid-state DNP which consists of a Fabry-Perot resonator for the microwave excitation and a stripline resonator for the NMR detection. This new double resonance structure (260 GHz/400 MHz) offers a 30-fold increase in aqueous sample volume (80 nl) with respect to the helical probe and exhibits improved NMR sensitivity and linewidth.
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Affiliation(s)
- Vasyl Denysenkov
- Institute for Physical Chemistry, Goethe University Frankfurt, Max von Laue Str. 7, 60438 Frankfurt am Main, Germany
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Lingwood MD, Sederman AJ, Mantle MD, Gladden LF, Han S. Overhauser dynamic nuclear polarization amplification of NMR flow imaging. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 216:94-100. [PMID: 22329973 DOI: 10.1016/j.jmr.2012.01.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 01/18/2012] [Accepted: 01/19/2012] [Indexed: 05/31/2023]
Abstract
We describe the first study comparing the ability of phase shift velocity imaging and Overhauser dynamic nuclear polarization (DNP)-enhanced imaging to generate contrast for visualizing the flow of water. Prepolarization of water by the Overhauser DNP mechanism is performed in the 0.35T fringe field of an unshielded 2.0T non-clinical MRI magnet, followed by the rapid transfer of polarization-enhanced water to the 2.0T imaging location. This technique, previously named remotely enhanced liquids for image contrast (RELIC), produces a continuous flow of hyperpolarized water and gives up to an -8.2-fold enhanced signal within the image with respect to thermally polarized signal at 2.0T. Using flow through a cylindrical expansion phantom as a model system, spin-echo intensity images with DNP are compared to 3D phase shift velocity images to illustrate the complementary information available from the two techniques. The spin-echo intensity images enhanced with DNP show that the levels of enhancement provide an estimate of the transient propagation of flow, while the phase shift velocity images quantitatively measure the velocity of each imaging voxel. Phase shift velocity images acquired with and without DNP show that DNP weights velocity values towards those of the inflowing (DNP-enhanced) water, while velocity images without DNP more accurately reflect the average steady-state velocity of each voxel. We conclude that imaging with DNP prepolarized water better captures the transient path of water shortly after injection, while phase shift velocity imaging is best for quantifying the steady-state flow of water throughout the entire phantom.
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Affiliation(s)
- Mark D Lingwood
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, CA 93106-9510, USA
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Krummenacker JG, Denysenkov VP, Terekhov M, Schreiber LM, Prisner TF. DNP in MRI: an in-bore approach at 1.5 T. JOURNAL OF MAGNETIC RESONANCE (SAN DIEGO, CALIF. : 1997) 2012; 215:94-99. [PMID: 22248644 DOI: 10.1016/j.jmr.2011.12.015] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 12/16/2011] [Accepted: 12/18/2011] [Indexed: 05/31/2023]
Abstract
We have used liquid state ("Overhauser") Dynamic Nuclear Polarization (DNP) to significantly enhance the signal to noise ratio (SNR) of Magnetic Resonance Imaging (MRI). For the first time this was achieved by hyperpolarizing directly in the MRI-scanner field of 1.5 T in continuous flow mode and immediately delivering the hyperpolarized substance to the imaging site to ensure maximum contrast between hyperpolarized sample and sample at thermal polarization. We achieve a maximum absolute signal enhancement factor of 98; while the hyperpolarized sample is transported at a flow rate of up to 30 ml/h yielding an average flow speed up to 470 mm/s over a distance of approximately 80 mm. A spatial imaging resolution of 100 μm with a signal to noise ratio of 25 was achieved on the flowing sample. Application to MRI contrast enhancement or microfluidic imaging can be envisaged immediately.
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Affiliation(s)
- Jan G Krummenacker
- Institute of Physical and Theoretical Chemistry and Center of Biomolecular Magnetic Resonance, Goethe University Frankfurt, Max-von-Laue-Str. 7, 60438 Frankfurt, Germany.
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Türke MT, Parigi G, Luchinat C, Bennati M. Overhauser DNP with15N labelled Frémy's salt at 0.35 Tesla. Phys Chem Chem Phys 2012; 14:502-10. [DOI: 10.1039/c1cp22332a] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hu KN. Polarizing agents and mechanisms for high-field dynamic nuclear polarization of frozen dielectric solids. SOLID STATE NUCLEAR MAGNETIC RESONANCE 2011; 40:31-41. [PMID: 21855299 PMCID: PMC3171565 DOI: 10.1016/j.ssnmr.2011.08.001] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 08/01/2011] [Accepted: 08/01/2011] [Indexed: 05/05/2023]
Abstract
This article provides an overview of polarizing mechanisms involved in high-frequency dynamic nuclear polarization (DNP) of frozen biological samples at temperatures maintained using liquid nitrogen, compatible with contemporary magic-angle spinning (MAS) nuclear magnetic resonance (NMR). Typical DNP experiments require unpaired electrons that are usually exogenous in samples via paramagnetic doping with polarizing agents. Thus, the resulting nuclear polarization mechanism depends on the electron and nuclear spin interactions induced by the paramagnetic species. The Overhauser Effect (OE) DNP, which relies on time-dependent spin-spin interactions, is excluded from our discussion due the lack of conducting electrons in frozen aqueous solutions containing biological entities. DNP of particular interest to us relies primarily on time-independent, spin-spin interactions for significant electron-nucleus polarization transfer through mechanisms such as the Solid Effect (SE), the Cross Effect (CE) or Thermal Mixing (TM), involving one, two or multiple electron spins, respectively. Derived from monomeric radicals initially used in high-field DNP experiments, bi- or multiple-radical polarizing agents facilitate CE/TM to generate significant NMR signal enhancements in dielectric solids at low temperatures (<100 K). For example, large DNP enhancements (∼300 times at 5 T) from a biologically compatible biradical, 1-(TEMPO-4-oxy)-3-(TEMPO-4-amino)propan-2-ol (TOTAPOL), have enabled high-resolution MAS NMR in sample systems existing in submicron domains or embedded in larger biomolecular complexes. The scope of this review is focused on recently developed DNP polarizing agents for high-field applications and leads up to future developments per the CE DNP mechanism. Because DNP experiments are feasible with a solid-state microwave source when performed at <20K, nuclear polarization using lower microwave power (<100 mW) is possible by forcing a high proportion of biradicals to fulfill the frequency matching condition of CE (two EPR frequencies separated by the NMR frequency) using the strategies involving hetero-radical moieties and/or molecular alignment. In addition, the combination of an excited triplet and a stable radical might provide alternative DNP mechanisms without the microwave requirement.
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Affiliation(s)
- Kan-Nian Hu
- Laboratory of Chemical Physics, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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van Bentum PJM, van der Heijden GHA, Villanueva-Garibay JA, Kentgens APM. Quantitative analysis of high field liquid state dynamic nuclear polarization. Phys Chem Chem Phys 2011; 13:17831-40. [DOI: 10.1039/c1cp22002k] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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45
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Kryukov EV, Pike KJ, Tam TKY, Newton ME, Smith ME, Dupree R. Determination of the temperature dependence of the dynamic nuclear polarisation enhancement of water protons at 3.4 Tesla. Phys Chem Chem Phys 2011; 13:4372-80. [DOI: 10.1039/c0cp02188a] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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46
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Türke MT, Bennati M. Saturation factor of nitroxide radicals in liquid DNP by pulsed ELDOR experiments. Phys Chem Chem Phys 2011; 13:3630-3. [DOI: 10.1039/c0cp02126a] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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47
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Dollmann BC, Kleschyov AL, Sen V, Golubev V, Schreiber LM, Spiess HW, Münnemann K, Hinderberger D. Spin‐Labeled Heparins as Polarizing Agents for Dynamic Nuclear Polarization. Chemphyschem 2010; 11:3656-63. [DOI: 10.1002/cphc.201000559] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Björn C. Dollmann
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany), Fax: (+49) 6131‐379‐100
| | - Andrei L. Kleschyov
- Second Department of Medicine, Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz (Germany)
| | - Vasily Sen
- Institute of Problems of Chemical Physics, Russian Academy of Science, Acad. Semenov av. 1, 142431 Chernogolovka (Russia)
| | - Valery Golubev
- Institute of Problems of Chemical Physics, Russian Academy of Science, Acad. Semenov av. 1, 142431 Chernogolovka (Russia)
| | - Laura M. Schreiber
- Johannes Gutenberg University Medical Center, Langenbeckstr. 1, 55131 Mainz (Germany)
| | - Hans W. Spiess
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany), Fax: (+49) 6131‐379‐100
| | - Kerstin Münnemann
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany), Fax: (+49) 6131‐379‐100
| | - Dariush Hinderberger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany), Fax: (+49) 6131‐379‐100
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Krahn A, Lottmann P, Marquardsen T, Tavernier A, Türke MT, Reese M, Leonov A, Bennati M, Hoefer P, Engelke F, Griesinger C. Shuttle DNP spectrometer with a two-center magnet. Phys Chem Chem Phys 2010; 12:5830-40. [DOI: 10.1039/c003381b] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Bennati M, Luchinat C, Parigi G, Türke MT. Water 1H relaxation dispersion analysis on a nitroxide radical provides information on the maximal signal enhancement in Overhauser dynamic nuclear polarization experiments. Phys Chem Chem Phys 2010; 12:5902-10. [DOI: 10.1039/c002304n] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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